Agricultural combine harvesters are large machines that harvest, thresh, separate, and clean agriculturally grown crops bearing grain. The resulting clean grain is stored in a grain tank arranged on the combine harvester. The threshed straw is usually either chopped and spread on the field across the width of the cutting tool or led around the straw chopper and laid on the field in a swath in an unchopped form, in order to be able to be taken up later with a baler. The crop residue remaining on the rear outlet of the cleaning device, such as chaff and small straw parts, is spread on the field by a chaff scatterer or led through the straw chopper and spread on the field.
DE 199 08 111 C1 describes a combine harvester with a straw chopper and two impeller blowers arranged laterally one next to the other and following the straw chopper for the widely spread discharge of the straw across the field. The outlet of the straw chopper and the inlet of the impeller blowers that are arranged in a housing and that comprise impeller paddles rotating about an approximately perpendicular axis are arranged in one plane for the purpose of transferring material without changing the direction. Casings that join between the impeller blowers into a front tip facing the straw chopper are mounted around the impeller blowers. In the rear region, the casings are separated, in order to discharge the straw onto the field. Above the impeller blowers there is a cover, while there is no cover on their bottom side.
In US 2007/0015556 A1, a combine harvester with a straw chopper is described in which the outlet of the straw chopper loads the subsequent impeller blowers from below on their periphery at an acute angle. Above the impeller blowers there is a cover, while on their bottom side there is no cover. The top-side cover is provided with a few openings through which the air conveying elements mounted above a rotating disk take in air. On the bottom side of the disk, the impeller paddles of the impeller blowers are mounted. The additional drawn in air should prevent crop residue from collecting between the disk and the upper cover or on the impeller paddles.
DE 10 2007 037 485 B3 shows a combine harvester in which the straw chopper discharges the crop residue in free fall and loads the impeller blowers in the axial direction at an acute angle.
WO 2008/156419 A1 describes a similar arrangement of the straw chopper and impeller blower, but the flow of crops downstream of the straw chopper is deflected by a baffle plate, so that it strikes the impeller blower in the axial direction, but at a relatively acute angle. Here, the middle part of the flow of crop residue is deflected less strongly than the outer part, in order to achieve that the speed of the crop residue already existing after leaving the straw chopper is used to the highest possible degree, in that the impeller blowers rotating inward with their front sides are loaded in front of the rotational axis with the outer part of the flow of crop residue, while the middle part of the flow of crop residue is thrown against the impeller blower in the region at the back of the rotational axis. The impeller blowers are arranged in housings that are open, apart from the deflection plates, on their axial end face on the side of the charge and that are closed on the other end face.
In the prior art, the impeller blowers are consequently covered by a cover on one axial end face at the rear half at which the crop residue is discharged takes place, while the other axial end face is not covered (that is, in the case of US 2007/0015556 A1, DE 10 2007 037 485 B3, and WO 2008/156419 A1 located on the side from which the impeller blowers are loaded by the straw chopper in the axial or radial direction at an angle and, in the case of DE 199 08 111 C1, on the bottom side). To this end, it has proven disadvantageous that the desired throwing range is not sufficient in all cases for covering the widths of modern cutting tools.